Classic Motorcycle Restoration Low Budget

We have here, BSA A65 Thunderbolt, 1967. I acquired this bike as you see it here. The engine has been taken out, it was stripped down, we’ll show you in a moment. It had a few issues, nothing serious. Plan is with this bike, is to over a period of no more than a couple of months, we’ll do an engine rebuild.

We’re a good way on with that at the moment and we’ll show you that. But we’re going to put the whole thing back together, put the engine back together.

And then we’re going to put it back in the frame, and have the bike on the road. And you can see. But we don’t need to spend a great deal on this.

I mean everything is in fairly good order. And when it is up together it would just be coated with an oil spray and just protected during in the winter and ridden, as that’s what they were for really. It’s only because we now see motorcycling as recreational, for a lot of people. But in the day you didn’t have a car you had a motorcycle, and it is your everyday means of transport. And that’s where, really, we’re trying to put this bike back on the road as an everyday bike.

As far as I’ve looked at it so far, the cycle parts are all in good order. I think it’s an American export model because it’s got the small tank, it’s got the raked back handlebars. But the Thunderbolt and the Lightning were very similar.

Thunderbolt was a single carburetor 650. It’s what came after the A10, the pre unit.

This is a unit construction engine. This model of bike, the A50 which is the 500 and the A65 the 650, that came into production early 60s. The A10 and the A7, the pre-unit models that were before this, were quite an expensive bike to produce. And Triumph had already decided to go unit construction, and I think BSA wanted to move on and to upgrade what they’d already got, because the A10 and A7 have been around for a long time. So this was a more modern motorcycle with 12 volt electrics.

I think it’s a little bit cheaper to produce because it’s just a unit construction. I think it’s all built in one. In a previous video we showed me honing out these cylinder bores. I did in fact use a finer stone and finish it off afterwards, and I’m going to get you to just have a look and you’ll see that the finish we’ve got now is very good. The reason we had to hone these out is because there was some seizure marks, and I’ll show you those in a moment.

But it’s 20 thou oversize, there’s no lip in the top of the bores, there’s no wear, and all I’ve done is just literally cleaned them up. If the camera can see down here there was originally a seizure. Well I put my fingernail there, there’s nothing there now at all.

You just see very light surface marks. That won’t affect it.

It won’t smoke and when we put this together I’ll show you that the bike will run as clean as anything. So we’re just going to put new rings in there. And I did show you the pistons previously. Now this is the right hand piston, and this is where it’s cleaned up, now that’s a good serviceable piston. With new rings that’ll be fine.

This is where we had the seizure. Now if you was racing bikes in a paddock, if you nipped up a bike, you would come in, you rip the head off the barrels off, and you clean that up and you do exactly the same as I’m doing now. And that will be out in the next session for racing. That is not going to be an issue, I’ve just taken high spots off that.

What’s important is the glands where the rings run.

These are the glands. And if the rings sit in there properly, and you’ve got a decent bore, she won’t be a problem. So that’s the right hand side. Left hand piston, very good. We are making sure everything that is necessary is done, but just to say, you don’t always think, ‘ah the bores need a rebore.

‘ You could end up opening that bore up to another 20 thou, going out to 40, new set of pistons. So you’re paying out for new pistons, complete with rings and a rebore, and that makes that really quite expensive. And all I’ve done is honed it out, new set of rings.

There’s a big difference in how much I’m spending and I’m not wearing those bores out by oversizing when I don’t need to. So right, come to the bottom end, the crank case assembly.

When I received the bike, and I picked it up, it was all in pieces. The engine had been stripped right down. Now what I’ve done so far is the bottom end itself, the cranks back in, the bearings, the cranks shimmed up.

So I’ve used the original shells, they weren’t worn. I have got some parts coming for this hopefully in the next week, then the next video you’ll see the barrels back on.

And, you know, it comes together again. So that’s the bottom end. And the gearbox is a cluster. And being unit construction, this all goes into one unit. The whole thing is one.

So this is a cassette, and you can build this lot up quite easily on the bench. And there’s one or two gears that I have replaced now.

If you look at some of the sliding dogs, these ones are just a little bit rounded, they’re fine. So I’ve built this up with some spare gears I had for it. So I’ve got a good bottom end.

It’s a good gearbox, sorry. So all the components in there are all good. So all we’re going to really need for this to put this in good order is a gasket set, tab washer set. I’m going to put a new sprocket on the gear box here, a 21 inch tooth sprocket. Set of 20 thou oversized rings.

The kickstart ratchet sprocket here, there is quite a bit of wear.

That’s where sometimes you find people will kick on a kickstart, won’t let it engage properly, kick a bit too quick, and they catch the tooth, it burns a little bit. Rather than being too rough, always come to your position with your foot to engage it, then kick it. Rather than that initial bang down, and the gears aren’t meshed properly. The head I’ve not looked at yet.

I’m just going to show you. I think it’s in fairly good order. There’s no broken fins or cracking. And you can see that carburation looks like it’s been fairly good. We’re going to drop out a valve then we can look at the seat of the valve, and see what the valve guides are like.

So we’re going to put a tool in there to take the spring out, and the collets out. So with a magnet now, I should be able to just pull those out. There’s one collet.

Here’s the other one. So now we’ve released both the collets, taken the tool away.

I just put my finger on there, and got the valve. Now what I’m going to show you now, is by pulling a valve up before taking it apart, there’s a lot of wear and tear in that guide. So it looks like we’ll be replacing all four guides anyway. And that is really bad. Yeah, it’s done quite a bit of work.

But, the seats themselves, as they were cut out they’d be fine. We’ve just dropped the spring out now. I’ve just relieved the valve springs. You have a second spring, primary spring in here. And the main spring.

And the bottom cup is still on top of the valve guide. So hopefully, a pair of pliers, I’ll just get in there… and lift that away.

With reference to what I showed you just now with extensive valve guide wear, when we have this amount of wear it’s so easy to think, because you’re burning a lot of oil, you think that your engine, ‘oh it’s got to be rings, it’s got to be scored.’ So you’re in a hurry actually take the barrels off and look at the rings, and the rest of it. It’s not as far down as that. It’s in the top end.

It’s in the head.

This head, an ally head, with worn guides will rattle like mad. And you might think to start with it’s like you’re tappet adjustment is out. You’re not going to get a proper tappet adjustment really, because this is wobbling about so much. When that’s in operation that’s going to be all over the place. It’s going to be pinging, making all sorts of horrible noises like this.

And that poor old valve is not going up and down straight anyway. It’s wobbling about. So it’s very easy to think that you’ve got more going on than you really have. Just look at your valve guys, don’t just take your head off. Take your valve springs out.

Check your valve in your guide, and make sure that’s good before you go any deeper really.

Because what you’ll find is once you’ve got the head off, you’ll move the piston. You think actually there’s not a lot of wear there. There’s not a lot of movement. Get your head sorted out first.

If your head seems to be, you know, like you can’t see any score marks in the barrel, and not excessive movement, it will all be oil because it’s dropped down from the valve guide. But it’s more likely to be all located in the top here. So yeah, it’s the one that it can get missed a little bit. And it’s easily rectified.

But the head itself is good, so that could be refurbished quite cheaply really.

And like I say, reference, you’ve got an old oven, a small oven, but I’ve got an oven in the back here that I don’t use. I’ll chemically get that nice and clean so there’s no smell, and I heat it up in the oven, and get that really nice and warm. Then I’ll drift those valve guides out. They’ll come out because you’re expanding aluminium. When we come to taking these valve guides out, when it’s been in the oven it’s nice and hot take, it out, get it on the bench.

This is not the right diameter so I need to make another one of these. But just spin on the lathe. Piece of brass, and you do this dimension the same size as the valve itself so it’ll fit down into the guide with a nice good fit. It wants to go down a good way because you want to support this before you drift it out.

So imagine this is the right size exactly, nice kiss fit, down inside.

So we put that down inside and it’s held nice and straight. You can give it a good drift out. Because that’s fairly hot you do this fairly quickly. That guide will come out quickly. So we’ll do all four very, very quick.

We won’t do it today because we haven’t got the new guides. But when it’s all cleaned up, when we get new guides, we’ll take these ones out and we’ll show you what we do.

Once we’ve put new guides in we need to recut these seats, the valve seats. And the new valves will have to be just lapped in, that’s all. But a piece of brass is always good for that job.

Don’t use steel, use a piece of brass. Just looking at the actual bike itself, the chassis, you know, the rolling chassis we’ve got here. I’ve not looked at it really. It’s not in bad order. All I’ve done so far is literally just taken the seat off.

And I’ve taken, there’s a rack on the back, I’ve taken that off. And I’m in the process of putting a Commando handrail on the back because it’s quite handy when you put onto the main stand.

And if you take a pillion they’ve got somewhere to hold on to. So they’re just going to modify it to fit. I’ll show you that in a moment a bit more.

But, getting back to this like swing arm bushes, like here is your swing arm. And I can’t actually feel any movement so the swinging arm is good. That’s all in good order. You know it hasn’t got any bearing wear in the bearings. You know, the brake plate, that is actually loose on the shaft so it just wants a washer underneath there.

Yeah, it’s had a few modern components put on this. It’s got electronic ignition. And so yeah, it’s done away with the points assembly, so that’s not a bad thing. So it’s been upgraded a little bit. Mud guard and the frame are in good order.

The patina is nice. That’s what I want to try and keep really. So I don’t want to do it up. It’s nice have a bike, like I say, that you can just ride and not worry about.

Or just an oily rag, WD40, squirt over it, wipe it over.

Oil tank here. Yeah, we can put new lines on here. New feed and return. It had been modified to an oil filter. I’ll do away that because oil changes are so cheap on these things, aren’t they.

And the oil is the lifeblood of any engine. So I believe in changing it more regularly really, rather than trying to make it last longer. A pair of coolers here because it’s cooled ignition rather than on the A10 we talked about earlier, which is a magneto. So we got 12 volt electrics here. Single carburetor.

Tiny little tank. But the frame, yeah, we’re not going to do anything with this. Hasn’t got any rust factor in it, but the rims are slightly lifted a little bit for chrome, but it doesn’t matter. Got a nice brake on the front. And the gators probably could do with replacing at some stage.

But that could be done at a later time. Seat’s in quite good order. The underside, what we call the seat tray, itself, it’s got some repair work here actually looking at it closely. I probably will actually do this better. Grind this down.

We’ve got these spider cracks. Grind that right off and reweld that. The tank is a chrome tank. There’s a little bit of black paint on it but it’s in really good order. Because we haven’t got the engine in the frame, it’s a little bit difficult lifting this back without this falling off the bench.

But just going to give you an idea what it’s like on the front, the forks. So we’re going to do a similar thing to what we do on most bikes, is just lift this off the ground a little bit. Pull on the forks. It’s pulling on the main stand so got to be a bit careful.

But I can’t feel any movement on those fork leg bushes.

And if I do this again, I’m looking for movement and head race bearings. Just bearing in mind the damper is off. I can’t feel any lumpiness. I’ve got my wheel clamp here in the way a little bit, but what we’ll do with this anyway, we will pack it with grease. I will make sure this is okay.

I probably will take that apart and pack that with grease. But there’s no wear, and if I lift up the front wheel off the ground, a little bit off the bench, and spin the wheel, it’s got a tiny little buckle in there. But nothing to worry about. And the wheel bearings are good. We’ve got the bike on the main stand here but I’ve noticed that the side stand has got a cable tie on it.

This like here should be brazed to the frame. Well it’s broken. The braze is broken. What we’ll do is we’ll position this in the correct position. And we’ll redo this before we put the engine back in the frame.

We’ll take this paint back off here because it has been repaired in the past. Now we drop the bike down on the bench onto the floor height you can see no rev counter just a speedo and the pod. It’s a rubber pod here. It’s cracked, it’s a bit perished. So we might get another one of those.

But the headlight, everything else, yeah, it’s all nice. It’s in good order. The switch works okay. Whether this is original I don’t know.

But it has a tool pouch, which is quite handy.

Exhaust system, a little bit tatty. These are the down pipes, and these are actually not too bad. They will clean up. But on most of the models this should be a balance pipe. These ones haven’t got that, doesn’t need it.

A lot of people that want a replacement system won’t have that. And the silencers, well these are Campbells. You can’t get Campbells anymore, and they are a really nice exhaust system.

They sound quite throaty. I’ve shown you where we are today with the engine and had a quick look at the bike itself.

The rolling chassis. Now, because I’ve done a bit of work on here already, got the crank back in, the timing gears, and the oil pump, the next stage will be to put the gearbox cassette back in. Then we can put the clutch in. And we’ll do this and I’ll take some pictures and show you along the way. We can get the alternator in properly.

Barrels, pistons, they’re up to where we are with the head. The head we can’t do at the moment. I haven’t got any new valve guides, and like I say, I’m going to have to make a tool up, knock those guides out, then we can install the new guides and cut the seats and show you that part of it.

But really basically you can build up the bottom end. So next time we’ll see you we’ll be a little bit further on.


Perform general repair and maintenance work on motorcycles Assist with washing and detailing motorbikes Diagnose problems with motorbike transmissions Troubleshoot issues with knocking and shimmying Handle maintenance tasks on fuel lines and tires Perform fluid change tasks and ensure that bolts are lubricated properly Confer with customers to determine problems with motorcycles to determine issues Start motorbikes in order to assess impending problems Inspect motorbikes to figure out repair needs Work with apprentices and mechanics in order to diagnose and fix problems Perform both preventative and regular maintenance on motorcycles and mopeds Select appropriate tools to handle repair procedures

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